The potential of recombinant antigens ESAT-6, MPT63 and mig for specific discrimination of Mycobacterium tuberculosis and M. avium infection.
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Adolescent↗
Biomedical subjects
T Mark Doherty
Publications and source records attributed to T Mark Doherty.
Selecting the components for a safe and efficient tuberculosis subunit vaccine--recent progress and post-genomic insights.
Prophylactic vaccination against tuberculosis with BCG gained much of the credit for the decline of TB in Europe. However, with TB resurgent in many parts of the world, better vaccines are urgently needed. To improve on BCG, a rapid, rational approach to vaccine discovery is needed. Fortunately, advances in the fields of molecular biology and computer science have spawned new disciplines: Genomics, Proteomics and Transcriptomics are transforming the ways in which candidate vaccine antigens are discovered. In this review, we discuss how these new approaches have accelerated the pace of antigen discovery and vaccine development, and highlight some of the most promising new candidate vaccines and vaccine targets.
Animals↗
Mycobacterium avium complex promotes recruitment of monocyte hosts for HIV-1 and bacteria.
In lymphoid tissues coinfected with Mycobacterium avium complex (MAC) and HIV-1, increased viral replication has been observed. This study investigates the role of MAC in perpetuating both infections through the recruitment of monocytes as potential new hosts for bacteria and HIV-1. Increased numbers of macrophages were present in the lymph nodes of patients with dual infection as compared with lymph nodes from HIV(+) patients with no known opportunistic pathogens. In a coculture system, monocyte-derived macrophages were treated with HIV-1 or M. avium and its constituents to further define the mechanism whereby MAC infection of macrophages initiates monocyte migration. Monocyte-derived macrophages treated with bacteria or bacterial products, but not HIV-1, induced a rapid 2- to 3-fold increase in recruitment of monocytes. Pretreatment of the monocytes with pertussis toxin inhibited the migration of these cells, indicating a G protein-linked pathway is necessary for induction of chemotaxis and thus suggesting the involvement of chemokines. Analysis of chemokine mRNA and protein levels from M. avium-treated cultures revealed MAC-induced increases in the expression of IL-8, macrophage-inflammatory protein (MIP)-1alpha, and MIP-1beta with donor-dependent changes in monocyte chemotactic protein-1. Pyrrolidine dithiocarbamate, an antioxidant, inhibited the activation of NF-kappaB and significantly diminished the MAC-induced chemotaxis, concurrently lowering the levels of monocyte chemotactic protein-1 and MIP-1beta. These data demonstrate that MAC induces macrophage production of multiple chemotactic factors via NF-kappaB to promote monocyte migration to sites of MAC infection. In vivo, opportunistic infection may act as a recruitment mechanism in which newly arrived monocytes serve as naive hosts for both MAC and HIV-1, thus perpetuating both infections.
Cell Movement↗
Tuberculosis vaccine development.
If the end of the 20th century saw the flowering of genomics, the beginning of the 21st century is witnessing an equally rapid blossoming of proteomics. These twin technologies have had a dramatic influence on the study of tuberculosis (TB), and nowhere more so than in the development of new TB vaccines. Only a few years ago, it was generally accepted that clinical trials of new TB vaccines would not take place for at least a decade. However, the first trials are now scheduled to start within months. Much TB vaccine research has thus shifted from developing new vaccines, to selecting the best vaccines for human use from the increasing number of effective new candidates becoming available. This selection is being eased by the improved animal models that have been developed over the past few years and by our increasing understanding of immunity to TB.
Animals↗
Oral vaccination with subunit vaccines protects animals against aerosol infection with Mycobacterium tuberculosis.
Immunity against Mycobacterium tuberculosis depends largely on activation of cell-mediated responses, and gamma interferon has been shown to play a crucial role in this process in both humans and animal models. Since the lung is normally the organ in which infection is initiated and is the major site of pathology, immune responses in the lung play a significant role in restricting initial infection with M. tuberculosis. The aim of the present study was to stimulate efficient immunity in the lung by targeting the gut mucosa. Detoxified monophosphoryl lipid A (MPL) has been shown to be a relatively nontoxic adjuvant which efficiently promotes the induction of type 1 responses when it is given by the traditional subcutaneous route. We have therefore compared subcutaneous immunization of mice to oral immunization by using a model subunit vaccine carrying two immunodominant proteins from M. tuberculosis, in combination with MPL-based adjuvants. While less effective when used to prime a response, a heterologous priming and boosting vaccination strategy employing oral boosting induced significant systemic type 1 responses which equaled and surpassed those attained by subcutaneous immunization protocols. Moreover, the increased immune responses observed correlated with the induction of substantial protection against subsequent aerosol infection with virulent M. tuberculosis at levels comparable to, or better than, those obtained by multiple subcutaneous vaccinations. These results demonstrate that booster vaccinations via mucosal surfaces, by combining efficient subunit vaccines with the potent adjuvant MPL, may be an effective method of addressing some of the shortcomings of current vaccination strategies.
Acyltransferases↗
Immune responses to the Mycobacterium tuberculosis-specific antigen ESAT-6 signal subclinical infection among contacts of tuberculosis patients.
Diagnosis of latent Mycobacterium tuberculosis infection is considered essential for tuberculosis control but is hampered by the lack of specific reagents. We report that strong recognition of tuberculosis complex-specific antigen ESAT-6 by healthy household contacts of tuberculosis patients correlates with the subsequent development of active tuberculosis during a 2-year follow-up period.
Antigens, Bacterial↗